Carbon black has been used as a black pigment. In recent years, a carbon black pigment that is provided with improved dispersibility in water (i.e., polar solvent) via surface modification has been developed as a black coloring material for inkjet printers and the like.
An improvement in dispersibility of carbon black in a non-polar solvent or a low-polar solvent has also been desired. For example, development of dispersible carbon black used for a composition (e.g., ink or paint), a color filter black matrix, a display device, and the like has been desired.
For example, JP-A-8-337624 discloses a carbon black graft polymer that exhibits excellent dispersibility in a medium used for an ink, a copier toner, a paint, a resin coloring agent, and the like, wherein the carbon black graft polymer contains a polymer portion that contains a silicone component and carbon black, and has a breakdown voltage of 0.5 kV/mm or more when dispersed in a silicone oil. This carbon black graft polymer is provided with sufficient dispersibility even in a low-polar solvent by incorporating the polymer chain of the silicone component in the polymer portion of the carbon black graft polymer.
JP-A-9-272706 discloses a reactive carbon black graft polymer obtained by reacting functional groups on the surface of carbon black with a polymer that contains a segment (A) having a group (1) reactive with functional groups on the surface of carbon black and a segment (B) having a chain structure differing from that of the segment (A), wherein the segments (A) and (B) have a group (2) reactive with a matrix of a desired medium.